The mechanism of visual adaptation has been conceived as primarily determined by the characteristics of the rods and cones and the dynamic properties of the various retinal neural elements. Such adaptation effects are short-lived and their duration is maximally 30-40 minutes required for complete dark-adaptation following conventional bleaching level light exposures. Contingent aftereffects (CAE) that involve moderate exposures to correlated color/spatial pattern stimuli, although relatively weak in magnitude, may persist for hours or days. The objective of the proposed psychophysical experiments with human observers is to explore both the temporal sequencing of the adaptation stimuli and the separate and correlated chromatic and spatial variables to determine the cause of the orders-of-magnitude shift in aftereffect decay time.